import java.util.Scanner;

public class Main1300 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        if (n>=90){
            System.out.println(n*3);
        }else if (n>=80&&n<90){
            System.out.println(n*2);
        }else if (n>=70&&n<80){
            System.out.println(n);
        }else if (n<50){
            System.out.println("50");
        }
    }
}
